excessive flow of milk from the breast, or lactation that is not associated with childbirth or nursing. The abnormal production of milk in women is usually due to excessive levels of estrogen in the body or to excessive production of prolactin, a hormone that is manufactured by the pituitary gland and that stimulates the production of milk. Galactorrhea may also be caused by a tumour or other disorder occurring in the pituitary gland. The milk of a nursing mother who has galactorrhea may be watery, whitish green in colour, and of poor quality